Total synthesis of AI-77-B

A new stereoselective approach for the synthesis of AI-77-B has been described. Dihydroisocoumarin fragment was made in two routes using Heck reaction followed by oxidation of the olefin and LDA mediated reaction. The chiral amino acid moiety has been obtained from d-ribose involving Grignard reaction on ribosylimine. Finally, condensation of dihydroisocoumarin with acid fragment furnished the title target AI-77-B.